1. Field of the Invention
The present invention relates to a coating system, and more specifically a coating system which coats a continuously running belt like substrate (hereinafter referred to as a web) with liquid composites (hereinafter referred to as coating liquids) using coating heads in particular in manufacture of films for photographic sensitized materials, photographic printing paper or the like.
2. Description of the Related Art
Precision coating methods for coating webs using coating dies are represented by a slot coating method, a slide bead coating method and a curtain coating method. Out of these coating methods, an optimum method is selected dependently on characteristics of a coating liquid applied on a product, for example, a water-based coating liquid or an organic solvent-based coating liquid, a number of coating liquid film layers, a viscosity of a coating liquid, a coating thickness, a coating speed or the like. Used for these coating methods are different coating heads and different kinds of coating operations respectively. In the slot coating method or the slide coating system method, for example, coating is started by moving a coating head or a backup roller opposed thereto from a standby position to a coating position. In the curtain coating method, on the other hand, it is necessary to move a coating head from a preparatory adjusting position to a coating position, and receive a coating liquid with a coating start plate before coating and operate a coating system by pulling out the coating start plate at a measured timing at a coating time. In order to measure the timing accurately in this case, the coating start plate may be pulled out with the coating head once stopped and then the coating head may be moved again to a final coating position. A moving speed and a moving distance of the coating head or the backup roller optimum for starting coating are different dependently on the coating methods. For a certain coated product, a conveying speed and a liquid flow rate at a coating start time and air conditioning conditions at a drying step may be changed from those for a portion coated in a steady state in order to prevent a conveying roller from being contaminated by a leading end which is coated thick at the coating start time and not dried. For the slot coating method or the slide bead coating method in which a gap is narrow between the coating head and the web, it is general to slightly evacuate the coating head or the backup roller when a web joint portion passes during continuous coating, thereby preventing a coating film from being remarkably disturbed by passage of the joint portion. However, such evacuation is not necessary for the curtain coating method in which a tip lip of the coating head is apart from the web, and a movement of the coating head rather causes disturbance of the coating film.
It is desirable that the coating methods which require different conditions and operations for coating as described above are used in separate coating lines.
However, it is inevitable in a certain case to use these coating methods in a single coating line from an economical viewpoint and it is necessary in this case to use a plurality of different kinds of coating heads in exchange in the single coating line. Since the coating heads are exchanged by an operator, it is possible that the operator erroneously selects a coating head to be exchanged or erroneously sets an operation sequence of the coating system for a correct coating head. If a coating head is erroneously selected or an operation sequence is erroneously set, not only coating will be unsuccessful but also there will be posed problems that the coating head will strike against the backup roller, thereby breaking appliances such as the coating head, the backup roller and the like.
The present invention has been achieved in view of such circumstances and has an object to provide a coating system and a coating method which selects kinds of coating heads and operation sequences with no errors even when two or more kinds of coating heads are used in exchange in a single coating line.
In order to accomplish the above described object, the present invention is directed to a coating system, comprising: a single coating line configured to coat a running web with a coating liquid using a plurality of different kinds of coating heads in exchange; and an automatic discriminating device which automatically discriminates at least kinds of the plurality of coating heads, the automatic discriminating device being disposed in the coating line.
According to the present invention, the automatic discriminating device is provided for automatically discriminating at least the kinds of the plurality of coating heads used in exchange in the single coating line, thereby the coating system is free from erroneous discrimination of the kind of the coating head which is set in the coating line.
Preferably, the coating system further comprises a control device which controls the coating line, the control device selecting an operation sequence corresponding to the automatically discriminated coating head out of a plurality of operation sequences according to an automatic discrimination result of the kind of the coating head set in the coating line.
Preferably, the control device comprises: an input device which allows an operator to input the operation sequence; and a check mechanism which checks whether or not the operation sequence inputted through the input device correctly corresponds to the kind of the coating head automatically discriminated by the automatic discriminating device. Accordingly, the coating system is capable of preventing an error that the kind of a coating head does not correspond to an operation sequence even when the operator inputs the operation sequence.
Preferably, the automatic discriminating device comprises: data carriers, each of which is disposed for each of the plurality of coating heads and has kind information of each of the plurality of coating heads; and a reading device which reads the information of the data carrier.
Preferably, each of the data carriers has coating condition information for each of the plurality of coating heads in addition to the kinds information of the coating heads. Thus, it can prevent an error that coating conditions of the coating heads do not correspond to the operation sequence, for example, even when an identical kind of coating heads, that is, coating heads for an identical coating method but configured for different coating conditions such as a coating width are used.
Preferably, the reading device comprises a read/write antenna, and the information set in the data carrier with one of a microwave system and an optical system is noncontactly read by the read/write antenna. Thus, it is free from limitation to locations for installing the data carrier and the read/write antenna.
Preferably, the automatic discriminating device comprises: bar codes, each of which is disposed for each of the plurality of coating heads and has at least kind information of each of the coating heads; and a bar code reader which reads information of the bar codes.
Preferably, the automatic discriminating device comprises: objects, each of which is disposed for each of the plurality of coating heads and has a form different dependently on each of the plurality of coating heads; and one of an electromagnetic proximity sensor, an ultrasonic sensor, a photoelectric sensor and a CCD camera which detects one of presence, absence and the forms of the objects.
Preferably, the automatic discriminating device comprises: one of an electromagnetic proximity sensor, an ultrasonic sensor, a photoelectric sensor and a CCD camera which determines forms of the plurality of coating heads.